Release v0.13.0

What's Changed

• Raise error for unknown region by @phackstock in #284
• Fix for general config failing without definitions by @phackstock in #288
• Add VariableCodeList.units attribute and tests by @danielhuppmann in #289
• Add link from model-mapping page to region-aggregation-attributes by @danielhuppmann in #292
• Prototype for a model-registration parser by @danielhuppmann in #285
• Use poetry by @phackstock in #293
• Fix typo in nightly tests by @phackstock in #296
• Update to pydantic v2 by @phackstock in #297

Full Changelog: v0.12.0...v0.13.0